The present invention relates to a wheel support bearing assembly equipped with at least one of a load sensor for detecting a load imposed on a bearing portion of a vehicle wheel and a torque sensor for detecting a torque acting on a shaft or axle.
Hitherto, in order to accomplish a control of an anti-lock braking system of an automotive vehicle and a control of the attitude assumed by the automotive vehicle during travel thereof, the wheel support bearing assembly has been well known, in which sensors are incorporated therein. Specifically, the wheel support bearing assembly has been suggested, in which the various sensors such as a temperature sensor and a vibration sensor are employed to detect, in addition to the number of revolutions (the rotational speed), various parameters useful for the travel of the automotive vehicle. (See, for example, the Japanese Laid-open Patent Publication No. 2002-340922.)
On the other hand, the wheel support bearing assembly is also known, in which for controlling the attitude of the automotive vehicle during the travel thereof, sensors for detecting the rotational speeds of wheels employed in the automotive vehicles. Also, in the general purpose wheel support bearing assemblies currently widely in use, a bearing assembly is furthermore known in which a torque sensor including magnetostrictive patterns, provided on an outer peripheral surface of an inner race, and a coil carried by an outer race is incorporated. (See, for example, the Japanese Laid-open Patent Publication No. 2001-33322.)
The control of the attitude of the automotive vehicle during the run thereof is difficult to achieve only with detection of the rotational speed of the automotive vehicle. In view of this, it is contemplated to achieve the attitude control in dependence on the load acting on the wheels of the automotive vehicle during the run thereof. By way of example, during the cornering, a relatively large load acts on the vehicle wheels on one side; during the travel on a non-leveled road surface, a relatively large load acts on the wheels on one side of the automotive vehicle; and during the braking, a relatively large load acts on the front wheels. Thus, the loads acting on the vehicle wheels are not even. Also, in the case that the vehicle carries unevenly-distributed load, the loads acting on the vehicle wheels may be uneven. For this reason, if the loads acting on the vehicle wheels can be detected at any time, the automobile suspension system or the like can be controlled based on the result of detection to accomplish the vehicle attitude control (prevention of the rolling of the automotive vehicle during the cornering, prevention of the front wheel sag during the braking, and/or prevention of the automotive body sinking or lowering brought about by uneven distribution of load). However, no suitable space for installation of those sensors for detecting the loads acting on the vehicle wheels is available and, therefore, the vehicle attitude control relying on the detection of the loads is difficult to realize.
On the other hand, even with the vehicle attitude control that is carried out by comparing the respective rotational speeds of the vehicle wheels, the proper vehicle attitude control is difficult. In order to accomplish the proper vehicle attitude control, an increased number of pieces of information on the operating condition of an automotive vehicle, or information that accurately reflects a change in attitude during the run of the automotive vehicle is required to be detected. However, in order to detect the operating condition information on various portions of the automotive vehicle, various sensors are necessary. Incorporation of sensors has problems with the space for installation thereof, installation work, wiring and so on. Considering that the automotive vehicle in general is strongly required to be mass-producible and lightweight, the demands therefor must be satisfied. Because of that, such problems have been encountered with as to what type of sensor should be selected for securing the information on the operating condition of the automotive vehicle and where such sensor should be installed, as a sensor to be added for the purpose of accomplishing the proper vehicle attitude control while the foregoing demands have been satisfied.